Claim CB200.4:

Source:

Response:

The complement system of the human immune system is not irreducibly
complex. Urochordates have a functional complement system, yet they
lack a component of the cascade.

Common mechanisms, such as gene duplication and co-option of molecules
with other roles, allow the immune system to evolve naturally. Much
has been written on the subject. (Kasahara et al. 1997; Lindsay 1999;
Travis 1998)

Behe gets some of the basic biology wrong. Bacteria are not destroyed,
as Behe says (1996, 134), by water rushing in when the cell membrane is
punctured, but because their chemical gradients have been destroyed
(Ussery 1999).